Prehistoric NASA Sandstone Proves Dinosaurs and Mammals Interacted With Each Other

Sometimes an amazing discovery is hiding in plain sight. This was the case with a slab of sandstone discovered just outside of NASA's Goddard Space Flight Center that contains at least 70 mammal and dinosaur tracks from more than 100 million years ago.

The stone was found by Ray Stanford, a local dinosaur expert whose wife, Sheila, works at Goddard. Ray spotted the unusual rock on a hillside next to Sheila's building. Upon parking his car to investigate, he found a 12-inch-wide dinosaur track on the exposed rock. Upon excavation, the slab was revealed to be 8 feet by 3 feet, and covered in preserved tracks.

According to a new study published today in Scientific Reports, the sandstone provides incredibly rare proof that mammals and dinosaurs interacted.

"Here we describe a remarkable, newly-discovered assemblage of Cretaceous tracks from the Patuxent Formation of Maryland," reads the study. "The assemblage from the Goddard Space Flight Center (GSFC-VP1) yields a diverse, high-density ichnofauna of ~70 dinosaur, pterosaur, mammal and indeterminate tracks: 26 attributable to mammals with diverse footprint morphologies, some in trackway configurations."

The first track Stanford found was of a nodosaur—"think of them as a four-footed tank," he said. The team later determined that a baby nodosaur print was visible beside and within the adult print, suggesting that they traveled together. Other dinosaur tracks included a sauropod, or long-necked plant-eater; small theropods, crow-sized carnivorous cousins of the Velociraptor and Tyrannosaurus rex; and pterosaurs, a group of flying reptiles that included pterodactyls.

Meanwhile, at least 26 mammal tracks have been identified on the slab since its discovery in 2012. Among them is the largest mammal track ever recovered from the Cretaceous period, about four square inches. Most of the footprints belong to what are commonly considered small mammals, about the size of a squirrel.

"It's a time machine," said Stanford. "We can look across a few days of activity of these animals and we can picture it. We see the interaction of how they pass in relation to each other. This enables us to look deeply into ancient times on Earth. It's just tremendously exciting."